This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in Japanese Patent Application number 2001-139740 filed on May 10, 2001 and Japanese Patent Application number 2001-139741 filed on May 10, 2001.
The present invention relates to an electric motor having a control device constituted by an electronic circuit.
The electric motor corresponds to an apparatus which converts an electric current supplied from a power source into a mechanical rotational motion so as to output, and is widely employed from parts for a motor vehicle such as a wiper system down to consumer appliances such as an OA device, an AV device and the like.
A motor assembly of a direct-current motor with brush corresponding to one kind of the electric motor mentioned above has a yoke. A permanent magnet is fixed to an inner peripheral surface of the yoke, and is structured such as to supply a magnetic flux to an inner portion of the yoke. Further, a rotor which is positioned in the magnetic flux and corresponds to an armature is rotatably received within the yoke, and the rotor is provided with a plurality of armature coils. Further, a commutator to which a plurality of commutator segments are radially mounted is axially attached to a rotary shaft of the rotor, and a plurality of brushes supported by a brush holder are slidably in contact with the commutator. Further, an electric current rectified by the commutator is supplied to an armature coil by supplying a direct current to the brushes, and an electromagnetic force is generated in the armature coil positioned in the magnetic field of the permanent magnet, whereby the rotor is rotated.
In the direct-current motor with brush, a motor controller for controlling an operation of the motor is connected to the motor assembly. The motor controller is independently provided from the motor assembly, and is provided therein with an electronic circuit, for example, a flat wiring substrate for switching a rotational direction of the rotor and performing an intermittent motion in the case of a direct-current motor with brush employed in a wiper apparatus provided in the motor vehicle.
In the direct-current motor with brush mentioned above, the motor controller is independently provided from the motor assembly, and is structured such as to be connected to the motor assembly by a wire having a connector or the like. Accordingly, in addition to the motor assembly, parts such as a casing of the motor controller, the wiring substrate, the connector, the wiring and the like are required, whereby a cost reduction of the direct-current motor with brush is prevented.
Further, since it is necessary to secure a motor controller mounting portion other than the mounting portion of the motor assembly, a freedom of placing the direct-current motor with brush become narrower.
An object of the present invention is to provide an electric motor in which a cost is reduced by reducing a number of the parts.
Another object of the present invention is to provide an electric motor in which a freedom of placement of the motor is increased.
In accordance with the present invention, there is provided an electric motor converting an electric energy into a mechanical rotational energy comprising:
a motor assembly having a motor housing which receives a magnetic field system for supplying a magnetic flux and having an armature provided with an armature coil; and
a control device, which is provided in an inner portion of the motor housing, and in which an electronic circuit for controlling the motor assembly is formed.
In accordance with the present invention, there is provided an electronic motor, wherein the electronic circuit is formed on an inner peripheral surface of the motor housing.
In accordance with the present invention, there is provided an electric motor, wherein the motor housing is formed by a yoke formed in a closed-end cylindrical shape and a lid member mounted to an opening end of the yoke, the lid member is formed in a closed-end cylindrical shape, and the electronic circuit is formed on an inner peripheral surface of the lid member.
In accordance with the present invention, there is provided an electric motor, wherein the lid member is made of a heat radiation material.
In accordance with the present invention, there is provided an electric motor further comprising:
a brush holder mounted to the lid member;
a brush holding portion fixed to the brush holder and having a connecting terminal provided at a position opposing to the lid member; and
a brush supported by the brush holding portion and slidably in contact with a commutator axially attached to a rotary shaft of the armature,
wherein the connecting terminal and the electronic circuit are connected by mounting the brush holder to the lid member.
In accordance with the present invention, there is provided an electric motor further comprising:
a rotary shaft to which the armature is fixed, and rotatably supported to the housing;
a commutator axially attached to the rotary shaft, and connected to the armature coil; and
a brush holder provided in an inner portion of the motor housing, and holding a brush slidably in contact with the commutator,
wherein the electronic circuit is formed in the brush holder.
In accordance with the present invention, there is provided an electric motor, wherein the brush holder is formed in a closed-end cylindrical shape, and the electronic circuit is formed on at least any one of an outer peripheral surface and a bottom surface of the brush holder.
In accordance with the present invention, there is provided an electric motor, wherein the brush holder is made of a heat-radiation and electromagnetic resistance material.
In accordance with the present invention, there is provided an electric motor, wherein the brush holder is formed of a metal plate and covered by a resin material.